I have been very attracted to the lifestyle and am fairly gregarious. My wife less so and she is NOT attracted to camping at all. My guess is that the folks with smaller rigs are more likely newcomers to the lifestyle and so may be a bit intimidated by those experienced folks with the land yachts. If/when I get a "starter" rig it will be just that...I like my Durango for it's comfort and economy and have poked around at lightweight trailers under 4,000 pounds loaded.
I have read that good, late model small units become available when people like me want to start out small and once they find that they like it, they want to trade up to bigger and better models. Others buy the new unit and find out that they don't like it and dump the equipment.